Cassette album sales continued to show growth in 2017, led by all things Guardians Of The Galaxy. Last year, cassette album sales rose by 35 percent to 174,000 copies sold, according to Nielsen Music. In 2016, there were 129,000 sold.

Still, cassettes remain an incredibly niche format, as they only comprised 0.10 percent of all album sales in 2017, and just 0.17 percent of physical album sales. That said, comparatively, in 2009, 2010 and 2011, cassette album sales numbered just 34,000; 21,000 and 31,000; respectively. So, while the format is still mostly a curiosity in 2017, it has made some sizable gains in recent years, and has seen some pretty major albums garner releases on cassette in the past few year or so. Among those: The Hamilton Mixtape compilation, Lana Del Rey’s Lust for Life and Taylor Swift’s Reputation.

Nielsen Music’s 2017 tracking year ran from Dec. 30, 2016 through Dec. 28, 2017. Numbers in this story are rounded. Nielsen Music began electronically tracking music sales and data in 1991 (so a reference in this story to the “Nielsen-era” means from 1991 to the present).

The second Guardians Of The Galaxy film’s companion album, Guardians Of The Galaxy Vol. 2: Awesome Mix, Vol. 2 led all cassette albums in sales in 2017, with 19,000 copies sold (see list, below). The Nos. 2 and 3 sellers were the first Guardians soundtrack, with 15,000 copies, followed by the Guardians Of The Galaxy: Cosmic Mix, Vol. 1 album with 5,000. (The Cosmic set is the soundtrack to the animated TV series.)

22 percent of all cassette album sales in 2017 were generated by the those three Guardians albums. Combined, they equaled 39,000 of all cassette album sales in 2017. The sizable sales for the Guardians albums on cassette makes sense, considering how the Awesome Mix tapes factor into the films’ storylines.

The Stranger Things, Volume One soundtrack is the year’s fourth biggest seller (3,000), while Eminem’s The Eminem Show is No. 5 with nearly 3,000. Rounding out the top 10 titles on cassette: an album that was clearly meant to be on cassette: The Hamilton Mixtape (just under 3,000), Prince and the Revolution’s Purple Rain soundtrack (2,000), Twenty One Pilots’ Blurryface (2,000), Kanye West’s Yeezus (2,000) and Nirvana’s Nevermind (2,000)